I made a map of the tectonic plates for my planet and then assigned each of them a direction. So as the question title says, what geographic features occur at each type of plate boundary?

Also to my knowledge, there are only 3 types of boundaries: convergent, divergent, and transform. However, I have not yet managed to figure out what type of boundary occurs when one plate's movement is perpendicular to another plate's and it is moving towards it. enter image description here Is it just a convergent, or some sort of combination between transform and convergent, or something else entirely?

  • $\begingroup$ Voting to close as off-topic. It's an awesome question and has many practical applications but there is an Earth Science SE that would better cater to this question. Additionally this does not seem to be in the context of worldbuilding - it's not completely "what if this happened", it's more of "how does this work" $\endgroup$
    – Zxyrra
    Nov 27, 2016 at 22:48
  • $\begingroup$ @Zxyrra just for clarification of where to ask future questions: should con-planet-ing type questions not be asked on the worldbuilding SE and instead be asked on the SE that directly relates to the topic? $\endgroup$ Nov 27, 2016 at 23:31
  • $\begingroup$ generally they're fine on here but this question seems almost exclusively within the realm of what we see on Earth, no fiction added $\endgroup$
    – Zxyrra
    Nov 27, 2016 at 23:39
  • $\begingroup$ on topic on both sites IMO. $\endgroup$
    – Vincent
    Nov 28, 2016 at 3:36

1 Answer 1



This creates a rift valley.

enter image description here

The best example is the one between the Arabian plate and the African plate. These two are separating and the result is the Red Sea. The African Rift Valley is actually the African plate splitting in two. The parts of East Africa and Horn of Africa will eventually be separated from the main African plate and form their own plate that will separate. This will cause the African rift valley to turn into a sea like the Red Sea, eventually.

If this happens mid ocean, the result is a mid-ocean ridge.


This is actually rare. The only place this is really happening is on the West Coast of North America. Here, there is slippage and subduction along the length of California. The result is a fracture zone where the Coast mountain ranges of California are beign pulled apart from the Sierra Nevada mountains and the Central Valley is forming in between them.

enter image description here

Eventually, the Central Valley will sink into an ocean, and the Coast range of California will be torn off into a new island...and new plate. The most notable thing about this area is the San Andreas Fault, one of the largest and potentially destructive faults in the world. There are, of course, other places with bad earthquakes, many of which are also around the Pacific Rim. Those earthquakes are caused by...


This is the specific situation you are asking about. Where either two plates are moving into each other or one plate is crashing into another plate that is not moving in the other direction, you have subduction. Here you have one plate submerge under another, driving up high volcanic mountains. Examples are the Cascades and Aleutian chain in British Columbia and Alaska, and the Andes in South America.

enter image description here

In particular, this happens with an oceanic plate meeting a continental plate. If it is two continental plates you get...

enter image description here

Continental collisions also cause maintain building; but the results are less volcanic. This is the process behind the Alps and mountains of the Balkans and Anatolia where the European and African plates are meeting. It is also famously the factor behind the Himalayas.

  • $\begingroup$ Umm... Central Valley is between Coastal Range and Sierra Nevada. Cascades are rather far North from this place. Meanwhile, San Andreas passes along the Santa Cruz mountains, way to the West of Coastal Range; I can see (however unlikely) that Santa Cruz coast could become an island, but nothing threatens Coastal Range and/or Central Valley. $\endgroup$
    – user58697
    Nov 26, 2016 at 3:34
  • $\begingroup$ @user58697 Corrected Cascades to Sierra Nevada in reference to the high mountains of California, thank you. Click the link on San Andreas Fault to see a map of the ranges and where they are shearing. By Coast Range I am referring to everything from Mendocino to Santa Barbara; the Traverse and Peninsular ranges will also split along the San Andreas Fault system. $\endgroup$
    – kingledion
    Nov 26, 2016 at 13:14
  • $\begingroup$ @user58697: I think Lassen & Shasta, and perhaps some of the volcanic territory to the south, are considered as part of the Cascades. $\endgroup$
    – jamesqf
    Nov 26, 2016 at 18:54

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